The biology of neuroblastoma will be investigated by establishing cell lines from tumors and characterizing them by biological and bio-chemical means. Cells will be hybridized to explore the mechanisms of differentiated cell functions and the possible involvement of an oncogenic virus in the etiology of the tumor will be taken into consideration. Membrane components of the cells will be isolated and used to study the patients' humoral and cellular immune responses against them in the search for tumor specific antigens.